Controlling Solid鈥揋as Reactions at Nanoscale for Enhanced Thin Film Morphologies and Device Performances in Solution-Processed Cu2ZnSn(S,Se)4 Solar Cells

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• 作者：Chengyang Jiang ; Yao-Tsung Hsieh ; Hongxiang Zhao ; Huanping Zhou ; Yang Yang
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：September 2, 2015
• 年：2015
• 卷：137
• 期：34
• 页码：11069-11075
• 全文大小：483K
• ISSN：1520-5126

文摘

Using Cu₂ZnSn(S,Se)₄ (CZTSSe) as a model system, we demonstrate the kinetic control of solid鈥揼as reactions at nanoscale by manipulating the surface chemistry of both sol鈥揼el nanoparticles (NPs) and colloidal nanocrystals (NCs). Specifically, we first identify that thiourea (commonly used as sulfur source in sol鈥揼el processes for metal sulfides) can transform into melamine upon film formation, which serves as surface ligands for as-formed Cu₂ZnSnS₄ (CZTS) NPs. We further reveal that the presence of these surface ligands can significantly affect the outcome of the solid鈥揼as reactions, which enables us to effectively control the selenization process during the fabrication of CZTSSe solar cells and achieve optimal film morphologies (continuous large grains) by fine-tuning the amount of surface ligands used. Such enhancement leads to better light absorption and allows us to achieve 6.5% efficiency from CZTSSe solar cells processed via a sol鈥揼el process using nontoxic, low boiling point mixed solvents. We believe our discovery that the ligand of particulate precursors can significantly affect solid鈥揼as reactions is universal to solid-state chemistry and will boost further research in both understanding the fundamentals of solid-state reactions at nanoscale and taking advantage of these reactions to fabricate crystalline thin film semiconductors with better morphologies and performances.